Parts mounting method and parts mounting apparatus

ABSTRACT

A suction head is inserted between first and second cameras relatively disposed facing one another with aligned optical axes, so that the first camera takes images of a head reference mark on the suction head, and the second camera of a first part suctioned to the suction head. Next, a stage is inserted between the first and second cameras so that the first camera takes images of a second part held on the stage, and the second camera of a stage reference mark thereupon. The relative positions between the first part and the suction head, and between the second part and the stage, are calculated based upon image information from the cameras, and the suction head and the stage are positioned, the first and second parts being relatively positioned based upon positional information and relative positional information from the first and second cameras, and mounting is performed.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a parts mounting method andparts mounting apparatus, used for mounting electronic parts onto aboard or the like.

[0003] 2. Description of the Related Art

[0004] Conventionally, for mounting electronic parts such assemiconductor chips, piezoelectric devices, or the like, on a board suchas a printed board, a positioning mechanism with high precision isnecessary for mounting such electronic parts at predetermined positionson the board.

[0005] Such a positioning mechanism is disclosed in Japanese Patent No.2,780,000 and another mechanism is disclosed in Japanese Patent No.2,811,856. With the mechanism disclosed in Japanese Patent No.2,780,000, two cameras take images of a specific mark from above andfrom below, respectively, so as to detect the offset between a workpieceand a board, and correction is performed for the relative movementamount between the workpiece and the board based upon the detectedoffset. On the other hand, Japanese Patent No. 2,811,856 discloses amethod wherein cameras are inserted into a position on a line formedbetween the board and an electronic part for taking images upward anddownward at the same time, i.e. a method wherein back-to-back camerastake images upward and downward at the same time.

[0006] However, with the positioning mechanism disclosed in the JapanesePatent No. 2,780,000, an axial mechanism with highly-preciserepeatability is necessary for moving the workpiece and the board, andfurthermore, the offset between the workpiece and the board cannot bedetected at the time of bonding. Furthermore, correction using thespecific mark is performed for detecting the relative positional offsetbetween the upper camera and the lower camera, and accordingly, themargin of error with regard to the distance between the upper camera andthe bonding unit due to thermal expansion or the like, and the margin oferror with regard to distance between the lower camera and the bondingstage due to thermal effects or the like, cannot be detected, andconsequently, there is a limit to the amount of improvement of precisionthat is available with regard to bonding.

[0007] On the other hand, with the mechanism disclosed in JapanesePatent No. 2,811,856, the back-to-back cameras are inserted into aposition in alignment with the workpiece and the board so as to detectthe offset therebetween, and accordingly, there is the need to retractthe back-to-back cameras to one side from this position in the alignmentat the time of bonding, so the positions of the workpiece and the boardcannot be detected at the time of mounting. Furthermore, since thecameras have back-to-back fields of view, the cameras cannot have thesame field of view in principle for taking an image of a singlecalibration mark, leading to the problem that the positioning of thesetwo cameras requires a complex operation.

SUMMARY OF THE INVENTION

[0008] Accordingly, the present invention provides a parts mountingmethod and a parts mounting apparatus, wherein highly-precisepositioning can be made with a configuration employing a low-costmovement mechanism for moving parts, the positions of a head and a stagecan be detected during mounting, and correction can be performed for themargin of error due to deformation of the head or stage, or the like.

[0009] To this end, a parts mounting method, wherein a first part issuctioned by a suction head, and positioning is performed so as to mountthe first part onto a second part held by a stage, comprises thefollowing steps: preparing a first optical system with an optical axisdirected toward the suction head from above, and a second optical systemwith an optical axis directed generally facing the optical axis of thefirst optical system, from below the stage; inserting the suction headbetween the first optical system and the second optical system so thatthe first optical system takes an image of a head reference markprovided to the suction head, which can be observed from above, and sothat the second optical system takes an image of the first partsuctioned to the suction head; inserting the stage between the firstoptical system and the second optical system so that the first opticalsystem takes an image of the second part held on the stage, and so thatthe second optical system takes an image of a stage reference markprovided to the stage, which can be observed from below; calculating therelative position between the first part and the suction head, and therelative position between the second part and the stage, based uponimage information from the first and second optical systems; detectingthe head reference mark and the stage reference mark by the first andsecond optical systems with the suction head and the stage beingpositioned at the mounting position, and performing positionalcorrection for at least one of the suction head and stage so that thepositions of the first part and the second part satisfy a predeterminedrelation using the detected positional information and the relativepositional information; and performing mounting for the first part andthe second part following the positional correction.

[0010] Further, a parts mounting apparatus, for positioning and mountinga first part on a second part, comprises: a suction head, having a headreference mark which can be observed from above, for suctioning thefirst part at the lower end portion thereof; a stage, having a stagereference mark which can be observed from below, for holding a secondpart at the upper end thereof; a driving mechanism for relatively movingthe suction head and the stage in the X, Y, Z, and θ directions; a firstoptical system for taking images of the second part held by the stage,and the head reference mark, from above the suction head; a secondoptical system, disposed so as to generally face the first opticalsystem with the optical axis thereof aligned with the optical axis ofthe first optical system, for taking images of the first part suctionedto the suction head, and the stage reference mark, from below the stage;a computation device for calculating the relative position between thefirst part and the suction head, and the relative position between thesecond part and the stage, based upon image information from the firstand second optical systems; and a control device for performingpositional correction for the suction head and the stage so that thepositions of the first part and the second part satisfy a predeterminedrelation based upon above-described relative positional information andpositional information from the first and second optical systemsdetecting the head reference mark and stage reference mark with thesuction head and stage being positioned at the mounting position. Suchan apparatus allows the above parts mounting method to be carried outwith a simple apparatus configuration.

[0011] Description will now be made regarding an example of the partsmounting method. First of all, with the example, a first optical systemand a second optical system are employed. Note that the optical systemmay include not only a camera main unit, but also may include mirrors orlenses, and furthermore, the optical system is not restricted to anoptical system including a single camera, but rather, an arrangement maybe made wherein two optical system include a single camera, or anarrangement may be made wherein an optical system includes multiplecameras.

[0012] The first optical system is disposed above a suction head, facingdownwards, and the second optical system is disposed below a stage,facing upwards. The first optical system and the second optical systemare disposed facing one another with generally aligned optical axes, andin a known positional relation. With the first optical system and thesecond optical system facing one another with generally aligned opticalaxes, each optical system should be disposed so that the optical axis isin the range of the field of view of the other optical system. In theevent that the size of one of a first part and a second part, which areto be mounted, is greater than the assumed viewing field, the firstoptical system and the second optical system should be integrally movedin the horizontal direction.

[0013] Next, the suction head is inserted between the first opticalsystem and the second optical system, so that the first optical systemtakes an image of a head reference mark which is provided to the suctionhead, and can be observed from above, and so that the second opticalsystem takes an image of the first part suctioned to the suction head.The first optical system and the second optical system are disposedfacing one another, with generally aligned axes, and accordingly, therelative position between the suction head and the first part can beobtained based upon the image data from these two optical systems. Notethat the arrangement wherein the suction head is inserted between thefirst optical system and the second optical system is not restricted tothat wherein the first and second optical systems are fixed and thesuction head is moved, but an arrangement may be made wherein thesuction head is fixed, and the first and second optical systems aremoved.

[0014] Next, the stage is inserted between the first optical system andthe second optical system, so that the first optical system takes animage of the second part held on the stage, and so that the secondoptical system takes an image of a stage reference mark which isprovided to the stage and can be observed from below. In this case, therelative position between the stage and the second part can be obtainedbased upon the image data from these two optical systems in the same wayas described above. Note that the arrangement wherein the stage isinserted between the first optical system and the second optical systemis not restricted to that wherein the first and second optical systemsare fixed and the stage is moved, but an arrangement may be made whereinthe stage is fixed and the first and second optical systems are moved.

[0015] Note that the step wherein the relative position between thesuction head and the first part is obtained, and the step wherein therelative position between the stage and the second part is obtained, maybe performed in any order. Furthermore, the head reference mark ispreferably provided at a position as close as possible to the first partsuctioned to the suction head, and the stage reference mark ispreferably provided at a position as close as possible to the secondpart. Furthermore, in a case of taking images of the first part and thesecond part, an arrangement may be made wherein alignment marks havebeen applied to these parts beforehand, or an arrangement may be madewherein the position of the part is detected by taking an image of acharacterizing point (e.g., edge or the like) of the part.

[0016] Next, the relative position between the first part and thesuction head, and the relative position between the second part and thestage, are calculated based upon image information from the firstoptical system and the second optical system. That is to say, theposition of the suction head (head reference mark) is detected basedupon the image information from the first optical system, and theposition of the first part is detected based upon the image informationfrom the second optical system, whereby the relative position betweenthe first part and the suction head can be calculated. Furthermore, theposition of the second part is detected based upon the image informationfrom the first optical system, and the position of the stage (stagereference mark) is detected based upon the image information from thesecond optical system, whereby the relative position between the secondpart and the stage can be calculated.

[0017] Next, positional correction is performed for the suction head andthe stage so that the positions of the first part and the second partsatisfy a predetermined relation based upon the above-described relativepositional information and positional information from the first andsecond optical systems detecting the head reference mark and the stagereference mark with the suction head and the stage being positioned atthe mounting position. Mounting is performed for the first part and thesecond part in this situation, and thus, mounting can be performed withthe first part and the second part being positioned in a highly-precisemanner without positional deviation one from another.

[0018] With the parts mounting method according to the presentinvention, positional correction is performed during mounting whiletaking images of the reference marks provided to both the head and thestage, and accordingly, the axial mechanism only needs to have onlysufficient positional resolution, and does not require highly-preciserepeatability. Thus, a low-cost axial mechanism can be employed.Furthermore, the margin of error with regard to repeatability due tothermal expansion or lost motion can be corrected during mounting. As aresult, the present invention can be applied even to mounting ofelectronic parts that require positional precision on the order ofsubmicrons.

[0019] There is no need to hold the first and second optical systems ina fixed positional relation at all times, but the positions of the firstand second optical systems should satisfy a known relation at leastwhile taking images. For example, an arrangement may be made wherein anyof the optical systems are temporarily retracted at the time ofinserting the head or the stage, following which the retracted opticalsystem is returned. In this case, there is the need to employing amovement mechanism of the optical system having repeatability.

[0020] Furthermore, positioning can be performed while the first andsecond optical systems take images, so the offset between the first andsecond parts can be detected during mounting. Accordingly, even in theevent that thermal deformation of the head or stage occurs due to heatfrom the heater at the time of bump-bonding process, for example, thethermal deformation is detected in real time so that positionalcorrection is performed for the first and second parts, and thus,positioning can be performed with high precision even under heating.

[0021] The head reference mark according to the present invention is notrestricted to a particular type of mark such as a colored mark, aprotrusion, a recessed portion, or the like, specifically provided tothe suction head, but rather, a part of the head, such as the edgethereof, can be used as a head reference mark. In the same way, thestage reference mark according to the present invention is notrestricted to a particular type of mark specifically provided to thestage, but rather, a part of the stage, such as the edge thereof, can beused as a stage reference mark.

[0022] Note that the term “position” according to the present inventionis generally used for the position in the X, Y, and Z directions, andthe attitude in the θ direction. Accordingly, the term “position”encompasses the attitude.

[0023] The parts mounting method may further comprise a step wherein asingle calibration mark, which can be observed from both above andbelow, is inserted between the first optical system and the secondoptical system so that both the first optical system and the secondoptical system take images of the calibration mark, thereby determiningan offset of the optical axes of the first optical system and the secondoptical system.

[0024] Even in the event that the first optical system and the secondoptical system have been adjusted beforehand so as to face one anotherwith aligned optical axes in a precise manner, occurrence of the offsetof the optical axes cannot be avoided due to passing of time or changein temperature, and furthermore, it is difficult to keep highly-precisepositional resolution on the order of submicrons. Accordingly, with thisarrangement, both the first optical system and the second optical systemdetect a single mark from the upper side and the lower side so as toobtain the offset of the optical axes of both the optical systems, therelative position between the first part and the suction head and therelative position between the second part and the stage are calculated,and furthermore, positional correction is performed for the suction headand the stage, and accordingly addition of the margin of error does notoccur, thereby enabling positioning with high precision.

[0025] Note that while calibration should be preferably performed foreach time of mounting in order to perform positioning with the highestprecision, an arrangement may be made wherein calibration is performedonce every predetermined number of times of mounting, or for once everypredetermined time period.

[0026] Also, the calibration mark may be provided to the suction head orthe stage. While the calibration mark may be provided to a member otherthan the suction head and the stage, however, in this case, a movementmechanism is necessary for inserting and retracting this member, leadingto complex configuration of the apparatus. Accordingly, with thisarrangement, the calibration mark is provided to the suction head or thestage, and accordingly, there is no need to provide a member other thanthe head and stage for calibration, and thus the arrangement has theadvantage of simple configuration.

[0027] Note that there is a need to observe the calibration mark fromthe upper and lower optical systems at the same time. Accordingly, withthe present arrangement, a vertical through hole provided to the suctionhead or the stage; however, a mark provided on a transparent member(e.g., glass plate), or the like, can be employed as a calibration mark.

[0028] An arrangement is preferably employed wherein the first opticalsystem and the second optical system are held in the fixed positionalrelation during the step wherein images of the head reference mark andthe first part are taken, the step wherein images of the second part andthe stage reference mark are taken, the step wherein positionalcorrection is performed for at least one of the suction head and thestage, and the step wherein mounting is performed for the first part andthe second part. That is to say, these optical systems are preferablyheld so that the offset of the optical axes of the optical systems doesnot occur during all the steps for positioning.

[0029] As described above, with the present arrangement, positionaldetection is performed by the first and second optical systems facingone another, with the fixed relative position therebetween at all times,there is little influence of the margin of error due to the movementmechanism as compared with this arrangement, wherein the optical systemsare separately moved, and thus, positioning can be performed withimproved precision, and furthermore, there is no need to provide ahighly-precise movement mechanism.

[0030] The positional correction step for the suction head and the stageat the mounting position may include a step wherein the first and secondoptical systems continuously take images of the head reference mark andthe stage reference mark while heating one or both of the suction headand the stage, with correction being performed with regard to therelative position between the suction head and the stage so that thepositions of the first part and the second part satisfy predeterminedrelation based upon the above-described relative positional information.

[0031] In this case, the offset between the marks corresponding tothermal deformation is continuously detected during mounting, andaccordingly, even in the event that thermal deformation occurs,positional correction can be made in real time, and thus, mounting canbe performed for the first part and the second part with high precisionat all times.

[0032] At least of the suction head and the stage may comprise apart-suction opening, a hollow portion which is provided behind a backside of the part-suction opening and communicates with the part-suctionopening, a transparent member which closes the end opposite thepart-suction opening of the hollow portion, where the part-suctionopening can be observed from the back side, and an air suctioning pathwhich is connected to the hollow portion, with at least one of the firstoptical system and the second optical system detecting the part-suctionopening as a head reference mark or a stage reference mark through thetransparent member.

[0033] That is to say, the part-suction opening is provided forsuctioning the first part or the second part, and is disposed at theposition closest to that part. Accordingly, even in the event thatthermal deformation of the suction head or the stage occurs, therelative positional offset between the part and the head (or stage) isreduced to the minimal value.

[0034] Furthermore, with this arrangement, the part-suction openingserving as a reference mark can be observed from the back side of thehead (or stage) through the transparent member, and accordingly, theoptical system can easily take images of the part-suction opening fromthe back side of the head (or stage) even during mounting. That is tosay, precise position of the head (or stage) can be detected duringmounting, thereby enabling positioning with high precision.

[0035] Also, a heater may be fixed near the part-suction opening. Insome cases, bonding is performed under heat and pressure at the time ofmounting the first part and the second part. In this case, the heater ispreferably provided at the position closest to the part, i.e., aposition near the part-suction opening, and accordingly, heat istransmitted to the part with optimal efficiency, thereby improvingbonding performance.

[0036] Note that in a case of heating the head (or stage), distortionoccurs in the image taken from the optical system due to wavering ofsurrounding air, leading to occurrence of margin of error. However, withthe suction head or the stage having the previous configuration having apart-suction opening, although the hollow portion is heated by theheater, the hollow portion is subjected to reduction of pressure by airsuctioning from the air suctioning path, and accordingly, the density ofair is reduced, whereby occurrence of wavering of air is reduced. Thus,at the time of taking an image of the part-suction opening through thetransparent member and the hollow portion, the margin of error due tothe wavering of air is reduced, thereby obtaining precise image data.

[0037] Further, the back face of the suction head or the stage ispreferably mounted to the driving mechanism by a bracket including ahollow portion whereby the first or second optical system can beinserted for taking images of said part-suction opening through thetransparent member.

[0038] While the head (or stage) is driven in the X, Y, Z, and θdirections by the driving mechanism, in the event that the head issupported by the driving mechanism by a cantilever configuration, theback side of the transparent member is opened, and thus, layout of thecamera, mirror, or the like, on the back side of the transparent membercan be easily performed. However, deformation of the head can occur withthe cantilever configuration due to the pressure applied at the time ofbonding of the first part and the second part, leading to difficulty inhigh-precision bonding. On the other hand, in the case that the head issupported at the back side thereof by the driving mechanism or the likeby a bracket, even in the event that the bracket is subjected toapplication of pressure, deformation of the bracket hardly occurs,thereby enabling bonding with high precision. However, it is difficultto dispose the camera or the like on the back side of the transparentmember due to interference with the bracket. Accordingly, with thisarrangement, the head is supported through a bracket having a hollowportion on the back side of the head, in particular, on the back side ofthe transparent member, and accordingly, interference does not occurbetween the camera and the bracket, whereby images of the part-suctionopening can be easily taken, and also the head (or stage) can besupported by the driving mechanism in a stable manner.

[0039] Note that the optical system according to the present inventionencompasses not only a camera but also portions having functions whereinimages are reflected toward the camera using mirrors or prisms.Accordingly, an arrangement may be made wherein only optical parts likemirrors, prisms or lens other than the camera are inserted into thehollow portion.

[0040] Other features and advantages of the present invention willbecome apparent from the following description of embodiments of theinvention which refers to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041]FIG. 1 is a perspective view of a mounting apparatus employing aparts mounting method of a first embodiment according to the presentinvention;

[0042]FIG. 2 is an enlarged view of a suction head and a stage of themounting apparatus shown in FIG. 1;

[0043]FIG. 3 is a perspective view of the suction head and the stageshown in FIG. 1;

[0044]FIGS. 4A through 4F are operational explanatory diagrams fordescribing a position-matching operation for the mounting apparatusshown in FIG. 1;

[0045]FIGS. 5A through 5F are operational explanatory diagrams fordescribing another position-matching operation for the mountingapparatus shown in FIG. 1;

[0046]FIG. 6 is a frontal view of a mounting apparatus employing a partsmounting method of a second embodiment according to the presentinvention;

[0047]FIG. 7 is a cross-sectional view taken along line VII-VII in FIG.6;

[0048]FIGS. 8A and 8B are enlarged diagrams of the suction head of themounting apparatus shown in FIG. 6, wherein FIG. 8A is an elevationalview thereof, and FIG. 8B is a cross-sectional view taken along lineVIII-VIII in FIG. 8A;

[0049]FIGS. 9A and 9B are enlarged diagrams illustrating a part-suctionopening provided to the suction head as viewed from the back side,wherein FIG. 9A is an elevational view thereof, and FIG. 9B is across-sectional view taken along line IX-IX in FIG. 9A;

[0050]FIG. 10 is a side view of a mounting apparatus of a thirdembodiment according to the present invention;

[0051]FIG. 11 is an image taken by a camera having a field of view shownin FIG. 10;

[0052]FIG. 12 is a perspective view of a mounting apparatus of a fourthembodiment according to the present invention;

[0053]FIGS. 13A through 13D are operational explanatory diagrams fordescribing the mounting apparatus shown in FIG. 12.

[0054]FIG. 14 is a cross-sectional diagram which illustrates an opticaldevice wherein mounting has been performed with the parts mountingmethod according to the present invention; and

[0055]FIG. 15 is a perspective view of a laser diode used as the opticaldevice in FIG. 14.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0056] First Embodiment

[0057]FIGS. 1 through 3 illustrate a mounting apparatus employing aparts mounting method of a first embodiment according to the presentinvention. Here, an electronic part P and a board B are employed as afirst part and a second part, respectively. The mounting apparatus ofthe present embodiment comprises a head unit 1 a, a stage unit 1 b,first and second cameras 20 and 21, and a control device 25.

[0058] The head unit 1 a includes a suction head 2 for suctioning theelectronic part P, and driving mechanisms 7, 8, and 9 for driving thesuction head 2 in the X, Y, and Z directions. As shown in FIG. 2, thesuction head 2 includes an unshown vacuum suction device and a suctionhole 3 connected to the vacuum suction device, wherein a part-suctionopening 4 is provided for suctioning the electronic part P by forming anopening on the lower face at the tip of the suction hole 3.

[0059] A head reference mark 5 is provided at a position on the upperface of the suction head 2, in particular, at a position generallycorresponding to the part-suction opening 4. For serving as the headreference mark 5, an arrangement may be made wherein multiple dot-shapedmarks are formed for detecting the repeatability in the θ direction asshown in FIG. 3. Furthermore, the head reference mark 5 may be formed ina directive shape (e.g., a rectangle or the like).

[0060] On the other hand, the electronic part P also has an alignmentmark P1 corresponding to the reference mark 5. The alignment mark P1 isnot restricted to a specific mark such as a dot-shaped mark, but rather,an arrangement may be made wherein a characterizing feature such as theedge of the electronic part P is used as the alignment mark P1.

[0061] The suction head 2 has a calibration mark 6 at the tip thereof(FIG. 2) for detecting the offset of the optical axes of the firstcamera 20 and the second camera 21, described later. The calibrationmark 6 can be detected from both the upper and lower directions, withthe calibration mark being formed of a through hole in the verticaldirection.

[0062] Note that an arrangement may be made wherein the suction head 2includes heating means for heating the electronic part P.

[0063] The suction head 2 is mounted on the X-axial driving mechanism 8through the Z-axial driving mechanism 7, and furthermore, the X-axialdriving mechanism 8 is connected to the Y-axial driving mechanism 9.Thus, the suction head 2 can be moved to any arbitrary position in theX-axial, Y-axial, and Z-axial directions. The suction head 2 can suctionthe electronic part P at an unshown supplying position, and cantransport the electronic part P to the mounting position so as to mountthe electronic part onto the board B.

[0064] The stage unit 1b includes a stage 11 for holding the board B,and driving mechanisms 15, 16, and 17 for driving the stage 11 in the X,Y, and θ directions. As shown in FIG. 2, the stage 11 also includes asuction hole 12 connected to an unshown vacuum suction device, and apart-suction opening 13 in the form of an opening formed on the upperface at the end of the suction hole 12 for suctioning and holding theboard B. A stage reference mark 14 is provided on the lower face of thestage 11, in particular, at the back position generally opposite to thepart-suction opening 13. For serving as the reference mark 14, anarrangement may be made wherein multiple dot-shaped marks are formed asshown in FIG. 3, or an arrangement may be made wherein a mark is formedin a directive form (e.g., rectangle or the like), in the same way aswith the head reference mark 5. Furthermore, an alignment mark B1 isprovided on the board B corresponding to the reference mark 14, as well.

[0065] Note that heating means may be provided to the stage 11 forheating the board B.

[0066] The stage 11 is mounted on the X-axial driving mechanism 15,wherein the two end portions thereof are respectively connected to theY1-axial driving mechanism 16 and the Y2-axial driving mechanism 17through hinges or the like. The Y1-axial driving mechanism 16 and theY2-axial driving mechanism 17 are movable independently from oneanother, whereby the stage 11 can be adjusted with regard to angle inthe θ direction. Thus, the stage 11 can be moved to any arbitraryposition in the X, Y, and θ directions. The stage 11 has functions forreceiving the board B at an unshown supplying position, and transportingthe board B to the mounting position.

[0067] The first camera 20 and the second camera 21 are mounted abovethe suction head 2 and below the stage 11, respectively. The cameras 20and 21 face one another with the optical axes thereof generally matchingone another, and the relative positions thereof are held by a suitablepositioning arrangement 22 such as a motor axis so that the cameras arenot relatively moved. Note that, while both the cameras preferablyinclude autofocus functions, an arrangement may be made instead whereinboth the camera 20 and 21 can be moved in the Z axis direction, makingthe autofocus functions unnecessary. In order to detect any offset ofthe optical axes of the first camera 20 and the second camera 21, thecalibration mark 6 provided to the suction head 2 is used. Note that anopening or mark formed on the stage 11 could also be used as acalibration mark, or a member other than the suction head 2 and thestage 11 could be used as a calibration mark.

[0068] The control device 25 acquires image data from the first camera20 and the second camera 21. From the acquired image data, the controldevice computes the offset of the optical axes of the first camera 20and the second camera 21, the position (attitude) of the electronic partP, the position (attitude) of the board B, the relative position(attitude) between the head reference mark 5 and the electronic part P,the relative position (attitude) between the stage reference mark 14 andthe board B, and the like, stores the calculated results, and controlsthe driving mechanisms 7, 8, 9, 15, 16, and 17.

[0069] Here, description will be made regarding an example of theoperation of the mounting apparatus having the above-describedconfiguration with reference to FIGS. 4A through 4F. FIG. 4A showscalibration processing for the first camera 20 and the second camera 21.First of all, the tip of the suction head 2 is inserted between thefirst camera 20 and the second camera 21, disposed at the mountingpositions, and images of the calibration mark 6 provided to the suctionhead 2 are taken by both the cameras 20 and 21 so as to obtain theoffset of the optical axes of the cameras 20 and 21. The offset of theoptical axes is used for calculating the relative position between theelectronic part P and the suction head 2, for calculating the relativeposition between the board B and the stage 11, for performing correctionof the positions of the suction head 2 and the stage 11, and the like,described later. FIG. 4B shows the state wherein the electronic part Psuctioned by the suction head 2 is inserted to a position between thecameras 20 and 21, i.e., the mounting position. FIG. 4C shows the statewherein the suction head 2 is moved downwards to a mounting level,wherein the first camera 20 detects the head reference mark 5, and thesecond camera 21 detects the electronic part P (alignment mark P1).Subsequently, the position (attitude) of the electronic part P and therelative position (attitude) between the electronic part P and thesuction head 2 are calculated based upon the image information from thefirst camera 20 and the second camera 21, and the calculated results arestored.

[0070]FIG. 4D shows the state wherein the suction head 2 is retracted toone side from the mounting position. FIG. 4E shows the state wherein thestage 11 is inserted to the mounting position, i.e., the position wherethe board B on the stage 11 can be detected by the first camera 20, andthe reference mark 14 on the back of the stage 11 can be detected by thesecond camera 21. At this position, the first camera 20 detects theboard B (alignment mark B1), and the second camera 21 detects the stagereference mark 14. Subsequently, the position (attitude) of the board Band the relative position (attitude) between the board B and the stage11 are calculated based upon the image information from the first camera20 and the second camera 21, and the calculated results are stored. Atthis time, correction is performed for the position of the board B sothat the position of the board B matches the position of the electronicpart P obtained in the state shown in FIG. 4C.

[0071] Note that the focal distances of the first camera 20 and thesecond camera 21 shown in the state in FIG. 4E are different from thefocal distances at the time of detecting the calibration mark 6 (seeFIG. 4A), respectively, and accordingly, both the cameras 20 and 21preferably have autofocus functions so as to clearly detect thealignment mark B1 and the stage reference mark 14.

[0072]FIG. 4F shows mounting processing, wherein the suction head 2 ismoved to the same position as in the state shown in FIG. 4C whilekeeping the stage 11 at the same position as in FIG. 4E, and theelectronic part P is mounted on the board B.

[0073] In the event that following detection of the position of theelectronic part P as shown in FIG. 4C, the cameras are moved to one sidefrom the mounting position as shown in FIG. 4D, and furthermore, thecameras are returned to the mounting position as shown in FIG. 4F, theelectronic part P might not be able to be returned to the mountingposition shown in FIG. 4C with suitable repeatability depending uponprecision of the driving mechanisms 7, 8, and 9. Furthermore, the fieldof view of the second camera 21 is interrupted by the stage 11, andaccordingly, the second camera 21 cannot directly detect the electronicpart P. Accordingly, in the mounting processing, the first camera 20detects the head reference mark 5, and the suction head 2 is moved inthe X and Y directions so that the position of the electronic part Pmatches that shown in FIG. 4C based upon the relative positional datacalculated in processing shown in FIG. 4C. The stage 11 is kept at thesame position shown in FIG. 4E. That is the position of the stage 11 atthe time of mounting is not offset from that shown in FIG. 4E, andaccordingly, correction should be performed for only the position of theelectronic part P. Note that in the event that offset occurs in the θdirection, the stage 11 should be moved in the θ direction. As describedabove, precise positioning can be performed for the electronic part Pand the board B, and accordingly, mounting can be made with highprecision, thereby enabling high-precision products to be manufactured.

[0074]FIGS. 5A through 5F show another example of the operation of theabove-described mounting apparatus. FIG. 5A shows calibration processingfor the first camera 20 and the second camera 21, wherein a calibrationmark 19 is provided to the stage 11. Accordingly, the first camera 20and the second camera 21 are moved to the mounting position, the tip ofthe stage 11 is inserted between the camera 20 and the camera 21, andboth the cameras 20 and 21 take images of the calibration mark 19provided to the stage 11 so as to detect any offset of the optical axesof the cameras 20 and 21. FIG. 5B shows the state wherein the stage 11is moved to the mounting position. Here, the first camera 20 takes animage of the board B (alignment mark B1) held on the stage 11, and thesecond camera 21 takes an image of the reference mark 14 provided on thelower face of the stage 11. The position of the board B and the relativeposition between the board B and the stage 11 are calculated based uponthe image information from the first camera 20 and the second camera 21,and the calculated results are stored. FIG. 5C shows the state wherein,immediately following the stage 11 being moved to one side from themounting position, the suction head 2 is moved to the mounting position.FIG. 5D shows the state of the suction head 2 being moved downwards tothe mounting level, wherein the first camera 20 detects the headreference mark 5, and the second camera 21 detects the electronic part P(alignment mark P1), at the mounting position. That is to say, theposition of the electronic part P and the relative position between theelectronic part P and the suction head 2 are calculated based upon theimage information from the first camera 20 and the second camera 21, andthe calculated results are stored.

[0075] Note that, at this time, the focal distances of the first camera20 and the second camera 21 are different from those at the time ofdetecting the calibration mark 19, and accordingly, the first camera 20and the second camera 21 preferably have autofocus functions in order toclearly detect the head reference mark 5 and the alignment mark P1.

[0076]FIG. 5E shows the state wherein the suction head 2 is moved upwardfrom the mounting level, and the stage 11 is moved to the mountingposition. Here, the stage 11 is moved in the X, Y, and θ directions sothat the position of the board B matches the position of the electronicpart P shown in FIG. 5D based upon the positional information stored inprocessing shown in FIG. 5B. FIG. 5F shows mounting processing, whereinthe suction head 2 is moved downwards so as to mount the electronic partP on the board B while keeping the stage 11 at the same position as inFIG. 5E. At this time, even in the event that the Z-axial drivingmechanism 7 for the suction head 2 is moved without sufficientrepeatability, the margin of error between the positions of thereference mark 5 in processing shown in FIG. 5D and FIG. 5F is detected,and furthermore, correction is performed in the X and Y directions basedupon the detected margin of error, whereby positioning with sufficientprecision can be performed. Thus, precise positioning is performed forthe electronic part P and the board B, thereby performing mounting withhigh precision.

[0077] In the positioning process shown in FIGS. 4A-4F and 5A-5F, in acase of mounting with heating, deformation of the suction head 2 or thestage 11 may be caused due to thermal expansion during mounting.Accordingly, even in the event that precise positioning has beenperformed immediately before mounting, precise matching might not beable to be performed for the electronic part P and the board B at thepoint in time that mounting has ended. As a countermeasure for theabove-described problem, a method described below can be employed in themounting processing (see FIG. 4F or FIG. 5F). First of all, the firstand second cameras 20 and 21 detect the head reference mark 5 and thestage reference mark 14, respectively, and temporary positioning isperformed for the suction head 2 and the stage 11 so that the positionof the electronic part P matches the position of the board B based uponthe above-described relative positional information. At this point intime, the electronic part P and the board B are only in soft contactwith each other. Next, pressing is performed while heating one or bothof the suction head 2 and the stage 11 (e.g., 350° C. for 5 seconds ormore), and the first and second cameras 20 and 21 continuously takeimages of the head reference mark 5 and the stage reference mark 14during pressing. During pressing, correction is performed for thesuction head 2 and the stage 11 with regard to the relative positiontherebetween so that the suction head 2 and the stage 11 are kept at thesame relative position as with the above-described temporary mounting.Thus, even in the event that deviation of the electronic part P occurs,the deviation is detected by the cameras 20 and 21 in real time, therebyenabling precise mounting of the electronic part P to be performed. Notethat, while description has been made regarding an arrangement whereintemporary mounting is performed with the electronic part P and the boardB being in soft contact with each other, an arrangement may be madewherein temporary mounting is performed with the electronic part P andthe board B not being in contact with each other, but with a small gaptherebetween.

[0078] Second Embodiment

[0079]FIGS. 6 through 9 shows a mounting apparatus of a secondembodiment of the present invention. The mounting apparatus of thepresent embodiment comprises a head unit 30, a stage unit 40, first andsecond optical systems 60 and 61, and a control device (not shown), inthe same way as with the first embodiment. The head unit 30 is made upof a suction head 31 for suctioning the electronic part P, a drivingmechanism 32 for driving the suction head 31 in the X, Y, and Zdirections, for example, and a bracket 33 for connecting the suctionhead 31 to the driving mechanism 32. The bracket 33 includes a pair ofsupport walls 33 a facing one another so as to define a hollow portion33 b therebetween, extending from one end to the other in the X-axialdirection. A mirror portion 60 c of the first optical system 60 isdetachably inserted into the hollow portion 33 b from the X-axialdirection.

[0080] As shown in FIG. 8, the suction head 31 comprises a base member34, a transparent plate 35 formed of a transparent glass or the like,secured to the upper face of the base member 34, a tube member 36 formedof a heat insulating material and secured to the lower face of the basemember 34, an attachment member 37 secured to the lower portion of thetube member 36, and a heater 38 mounted between the attachment member 37and the tube member 36. The aforementioned base member 34 is secured tothe lower end portion of the support walls 33 a with screws or the like.The attachment member 37 is preferably formed of a material with asexcellent thermal conductivity as possible.

[0081] The base member 34 includes a hole 34 a at the center portionthereof in the form of a through hole formed in the vertical direction,communicating with an internal hole 36 a of the tube member 36, whereinthe holes 34 a and 36 a form a hollow portion 39. The upper face of thehollow portion 39 is closed by the transparent plate 35. The base member34 is connected to an air pipe 34 b communicating with the hollowportion 39, wherein the air pipe 34 b is connected to an unshown vacuumsuction device, whereby an air suction path is formed.

[0082] The heater 38 includes a through hole 38 a at the center portionthereof, wherein the through hole 38 a is fitted to a hub portion 37 aprotruding at the center portion of the attachment member 37, andaccordingly, the heater 38 is disposed in the shape of a concentriccircle on the attachment member 37. A part-suction opening 37 b isformed in the form of a through hole at the center portion of the hubportion 37 a of the attachment member 37. The electronic part P issuctioned to the opening portion on the lower side of the part-suctionopening 37 b.

[0083] As described above, the hollow portion 39 communicating with thepart-suction opening 37 b is formed behind the part-suction opening 37 bof the suction head 31, and the end of the hollow portion 39, oppositethe part-suction opening 37 b, is closed by the transparent plate 35.The bracket 33 for connecting the head 31 to the driving mechanism 32includes the hollow portion 33 b, wherein the part-suction opening 37 bcan be easily observed by the first optical system 60 inserted into thehollow portion 33 b through the transparent plate 35. That is to say,the part-suction opening 37 b can be employed as a head reference mark.Note that the opening 37 b 1 (FIG. 9) on the upper side of thepart-suction opening 37 b is preferably formed in a directive shape suchas a rectangle or the like for in addition detecting the offset in anglein the rotational direction, as shown in FIG. 9.

[0084] The stage unit 40 comprises a stage 41 for suctioning and holdingthe board B, a driving mechanism for driving the stage 41 in the X, Y,and θ directions, for example, and a bracket 43 for connecting the stage41 to the driving mechanism 42. The stage 41 has avertically-symmetrical configuration as to the suction head 31 and thebracket 43 has a vertically-symmetrical configuration as to the bracket33, and accordingly, description regarding corresponding portions willbe omitted. That is to say, reference numeral 43 b denotes a hollowportion, 44 denotes a base member, 44 b denotes an air pipe, 45 denotesa transparent plate, 46 denotes a tube member, 47 denotes an attachmentmember, 47 b denotes a part-suction opening, 48 denotes a heater, and 49denotes a hollow portion. In this case, images of the part-suctionopening 47 b can be taken through transparent plate 45 by the secondoptical system 61 inserted into the hollow portion 43 b from the X-axialdirection, and accordingly, the part-suction opening 47 b can be used asa head reference mark, as well.

[0085] The first optical system 60 is mounted to a support portion 63provided on an XY-axial driving mechanism 62 through a Z1-axial drivingmechanism 64, the second optical system 61 is mounted to theaforementioned support portion 63 through a Z2-axial driving mechanism65. The first optical system 60 comprises a camera 60 a, a tube-shapedlens 60 b extending in the X-axial direction, and a prism or mirror 60 cmounted to the end of the lens 60 b, wherein the mirror 60 c is insertedinto the hollow portion 33 b of the bracket 33. With the above-describedconfiguration, light from the part-suction opening 37 b is reflected bythe mirror 60 c so that the camera 60 a can take an image of thepart-suction opening 37 b through the lens 60 b. The second opticalsystem 61 comprises a camera 61 a, a tube-shaped lens 61 b extending inthe X-axial direction, and a prism or mirror 61 c, with the mirror 61 cbeing inserted into the hollow portion 43 b of the bracket 43, in thesame way. Note that the mirrors 60 c and 61 c have small cross-sectionalareas as compared to the hollow portions 33 b and 43 b, and accordingly,the mirrors 60 c and 61 c are mounted with some leeway of space in theX, Y, and Z directions. Accordingly, even in the event that the suctionhead 31 and the stage 41 are moved at the time of positional detection,mounting, or correction of the position, any interference between thebracket 33 and the mirror 60 c, and between the bracket 43 and themirror 61 c, can be prevented.

[0086] The first optical system 60 and the second optical system 61 aresupported by the support portion 63 so that these optical systems faceone another with aligned optical axes, and relative movement is notcaused between these cameras in the X and Y directions. Furthermore, oneof the part-suction openings 37 b and 47 b provided on the suction head31 and the stage 41 may be used as a calibration mark in order to detectany offset of the optical axes of the first optical system 60 and thesecond optical system 61. Note that, in this case, there is the need toperform calibration with the electronic part P or the board B not beingsuctioned to the suction head 31 or the stage 41, as the case may be.Furthermore, the optical systems 60 and 61 can be integrally moved inthe X and Y directions by the XY-axial driving mechanism 62 in order tohandle processing for mounting multiple parts P on a large-sized boardB. Furthermore, the first optical system 60 can be adjusted in thevertical direction by the Z1-axial driving mechanism 64, and the secondoptical system 61 can be adjusted in the vertical direction by theZ2-axial driving mechanism 65, thereby enabling independent focusadjustment for the optical systems 60 and 61.

[0087] The operation of the mounting apparatus of the above-describedembodiment is generally the same as with the operation shown in FIGS. 4Athrough 4F and FIGS. 5A through 5F. Note that, in the event that thepart-suction opening 37 b of the suction head 31 or the part-suctionopening 47 b of the stage 41 is used for calibration, the suction head31 or the stage 41 is inserted between the upper and lower opticalsystems 60 and 61 with the electronic part P or the board B not beingsuctioned so as to perform measurement of the offset of the opticalaxes.

[0088] With the above-described embodiment, the part-suction openings 37b and 47 b are used as a head reference mark and a stage reference mark,respectively. The part-suction openings 37 b and 47 b are disposed atpositions closest to the electronic part P and the board B, andaccordingly, even in the event that some deformation of the suction head31 or the stage 41 occurs, the relative positional offsets between theelectronic part P and the suction head 31 and between the board B andthe stage 41 are reduced to the minimal value. Furthermore, with theabove-described embodiment, the part-suction opening serving as areference mark can be observed through the transparent plate from theback of the head (or stage), and accordingly, precise position of thehead (or stage) can be detected even during mounting, thereby enablingpositioning with high precision.

[0089] Furthermore, the suction head 31 and the stage 41 include theheaters 38 and 48, respectively, and thus, the electronic part P can bemounted on the board B under heat and pressure during mountingprocessing. In this case, the heaters 38 and 48 are disposed atpositions extremely close to the part-suction openings 37 b and 47 b,respectively, and heat is transmitted to the electronic part P and theboard B with optimal efficiency, thereby improving bonding performance.On the other hand, in the event of heating the head (or stage),distortion occurs in the image taken from the optical system due towavering of the surrounding air, leading to the occurrence of a marginof error. However, with the present embodiment, the hollow portion 39 issubjected to reduction of pressure by air suctioning from the airsuctioning path, and accordingly, the density of air is reduced, wherebythe wavering of the air is reduced. Thus, at the time of taking an imageof the part-suction opening 37 b through the transparent plate 35 andthe hollow portion 39, the margin of error due to the wavering of air isreduced, thereby obtaining precise image data.

[0090] Note that, while description has been made regarding theabove-described arrangement wherein the mirror portions 60 c and 61 cprovided to the first optical system 60 and the second optical system 61are inserted into the hollow portions 33 b and 43 b, respectively, in acase in which small-sized cameras can be employed, an arrangement may bemade wherein the lens units 60 b and 61 b, and the mirror units 60 c and61 c, are eliminated, and the cameras 60 a and 61 a are directlyinserted into the hollow portions 33 b and 43 b, respectively.Furthermore, while description has been made regarding an arrangementwherein the suction head 31 and the stage 41 have a symmetricalconfiguration one to another with respect to the vertical direction, andthe bracket 33 and the bracket 43 have a symmetrical configuration oneto another with respect to the vertical direction, an arrangement may bemade wherein any of the aforementioned components may have any arbitraryconfiguration according to the shape and the size of the first part(electronic part) P or the second part (board) B to be handled.

[0091] With the present embodiment, a support member having aconfiguration wherein support is performed with a pair of support walls33 a as described in the present embodiment is employed as each of thebrackets 33 and 43, and accordingly, the suction head 31 and the stage41 can be supported with a support configuration at both ends so as tobe connected to the driving mechanisms 32 and 42, respectively, wherebydistortion of the suction head 31 and the stage 41 due to application ofpressure during mounting can be prevented. Furthermore, the brackets 33and 43 have hollow portions 33 b and 43 b, respectively, where themirror portions 60 c and 61 c of the optical systems 60 and 61 can bedetachably inserted, and thus, the head reference marks 37 b and 47 bcan be easily observed during mounting.

[0092] Third Embodiment

[0093]FIGS. 10 and 11 illustrate a mounting apparatus of a thirdembodiment according to the present invention, wherein two opticalsystems have a single camera. The same components as in the secondembodiment shown in FIGS. 6 through 9 are denoted by the same referencenumerals, and description thereof will be omitted. With the presentembodiment, a camera 71, a lens 72, and mirrors (or prisms) 73 and 74for dividing the field of view of the camera 71 into halves in thevertical direction are disposed on a table 70 provided to the supportportion 63 so as to be movable in the Z-axial direction. The opticalaxis of the camera 71 is bent upwards by the mirror 73, and is bentdownwards by two mirrors (or prisms) 76 and 77 provided in an upperoptical system 75 which cannot be moved in the Z-axial direction,whereby the camera 71 can take an image of the head reference mark 37 b.On the other hand, the optical axis is bent downwards by the mirror 74and then is bent upwards by two mirrors (or prisms) 79 and 80 providedin a lower optical system 78 which cannot be moved in the Z-axisdirection, whereby the camera 71 can take an image of the stagereference mark 47 b. Thus, two optical systems can be formed with thesingle camera 71.

[0094]FIG. 11 shows an image example taken by the camera 71 havingabove-described field of view. The upper-half image corresponds to thehead reference mark 37 b, and the lower-half image corresponds to thestage reference mark 47 b. The table 70 is moved in the Z-axialdirection so that the optical path lengths of the upper and loweroptical systems match one another, and furthermore, the focus of thecamera 71 is adjusted by focusing in the Y-axial direction, wherebyfocusing can be performed for the images coming from the upper and thelower optical systems at the same time.

[0095] Fourth Embodiment

[0096]FIGS. 12 and 13 illustrate a mounting device of a fourthembodiment according to the present invention. With the presentembodiment, four cameras are employed in order to perform positioning ina short time. Description will be made below with reference to FIGS. 12and 13, while making a comparison with FIGS. 1 and 4, respectively. Notethat the same components are denoted by the same reference numerals, anddescription thereof will be omitted. In FIG. 12, a first camera 81 and asecond camera 82 are held by a suitable positioning arrangement 83 sothat these cameras face one another with aligned optical axes, and athird camera 84 and a fourth camera 85 are held by another positioningarrangement 86 so that these cameras face one another with alignedoptical axes. For example, the first camera 81 is used for detecting thehead reference mark 5, and the second camera 82 is used for detectingthe electronic part P suctioned by the suction head 2. Furthermore, thethird camera 84 is used for detecting the board B held by the stage 11and the head reference mark 5, for example, and the fourth camera 85 isused for detecting the stage reference mark 14. The relative positionsbetween the first camera 81 and the second camera 82, and between thethird camera 84 and the fourth camera 85, cannot be changed in the X andY directions, although relative movement therebetween is possible in thefocus direction.

[0097] Description will be made regarding the operation of theabove-described mounting apparatus with reference to FIGS. 13A through13D. FIG. 13A shows the calibration process, wherein the tip of thesuction head 2 is inserted between the first camera 81 and the secondcamera 82, and both the cameras 81 and 82 take images of the calibrationmark 6 provided to the suction head 2, whereby the offset of the opticalaxes of the cameras 81 and 82 is obtained. In the same way, the stage 11is inserted between the third camera 84 and the fourth camera 85, andboth the cameras 84 and 85 take images of the calibration mark 19provided to the stage 11, whereby the offset of the optical axes of thecameras 84 and 85 is obtained. FIG. 13B shows the state wherein theelectronic part P suctioned to the suction head 2 is inserted betweenthe cameras 81 and 82, and the board B held by the stage 11 is insertedbetween the cameras 84 and 85. In this situation, the relative positionbetween the head reference mark 5 and the electronic part P is detectedby the cameras 81 and 82, and the relative position between the board Band the stage reference mark 14 is detected by the cameras 84 and 85.FIG. 13C shows the state wherein the suction head 2 and the stage 11 aremoved so that positions of the electronic part P and the board B matchone another. While description will be made regarding an arrangementwherein the suction head 2 is moved to a position between the third andfourth cameras 84 and 85 so that the third camera 84 detects the headreference mark 5, and so that the fourth camera 85 detects the stagereference mark 14, an arrangement may be made wherein the stage 11 ismoved to a position between the first and second cameras 81 and 82 sothat the first camera 81 detects the head reference mark 5, and so thatthe second camera 82 detects the stage reference mark 14. FIG. 13D showsthe bonding process wherein bonding is performed while heating theelectronic part P and the board B.

[0098] An arrangement is preferably employed wherein the third andfourth cameras 84 and 85 continuously take images of the marks 5 and 14so as to adjust the positioning of the suction head 2 or the stage 11 inreal time so that deviation of the electronic part P from the board Bdue to heating does not occur.

[0099] As described above, with the present embodiment, the four cameras81, 82, 83, and 84 are employed, and accordingly, one pair of camerascan take images of the components of the suction head 2 while the otherpair of cameras take images of the components of the stage 11, therebyenabling positioning and mounting in a short time.

[0100]FIGS. 14 and 15 show examples of optical devices manufactured withthe parts mounting method according to the present invention. With thepresent example, a VCSEL (Vertical Cavity Surface Emitting Laser) diode90 (which will be referred to as an “LD” hereafter) is used as a firstpart, and an optical waveguide substrate 100 is used as a second part.As shown in FIG. 15, the LD 90 has an emission portion 91 at the centerportion on the main face thereof, from which a generally-conical emittedlight beam is cast. On the other hand, in the upper face of the opticalwaveguide substrate 100, light-introducing openings 101 are formed inthe vertical direction at predetermined intervals, and waveguides 102are formed inside the substrate 100 in the horizontal direction,orthogonal to the light-introducing openings 101. The LD 90 is bondedonto the upper face of the optical waveguide substrate 100 withelectroconductive bonding members (metal bonding member) 103 with thebottom up, and with the positions of the light-introducing opening 101and the emission portion 91 matching one another. The light emitted fromthe LD 90 is transmitted to an unshown optical communication circuitfrom the light introducing openings 101 through the waveguides 102.

[0101] In a case in which bonding is to be performed for theabove-described LDs 90 and optical waveguide substrate 100 with preciseposition-matching, a mounting method according to the present inventionis preferably employed. While description has been made regarding anarrangement in the first and second embodiment wherein alignment marksP1 and B1 are each provided to the first part P and the second part B,with the third embodiment, the emission portion 91 of the LD 90 can beused as an alignment mark, and the light-introducing opening 101 of theoptical waveguide substrate 100 can be used as an alignment mark, aswell. Accordingly, there is no need to provide any specific alignmentmark to the LD 90 or the optical waveguide substrate 100. In particular,with the LD 90, the position of the emission portion 91 is important.Note that, even in a case of providing a specific alignment mark at aposition other than the emission portion, in the event that margin oferror occurs between the alignment mark and the emission portion,precise mounting of the LD 90 onto the optical waveguide substrate 100cannot be performed. As described above, the emission portion 91 and thelight-introducing opening 101 are used as alignment marks, and thus, notonly are the mounting operations reduced, but also mounting can beperformed with improved precision.

[0102] While description has been made regarding an arrangement in theabove-described embodiments wherein one electronic part P is mountedonto one board B, the present invention also can be applied to anarrangement wherein multiple electronic parts P are mounted onto oneboard B in the same way. Note that, in this case, it is preferable toprovide respective alignment marks B1 to multiple mounting positions ofthe board B, and it is also preferable to provide multiple respectivestage reference marks 14 to the corresponding positions on the stage 11.

[0103] The present invention can be applied to various uses such as achip mounter for mounting electronic devices such as semiconductor chipsor the like onto a board, TAB bonder, flip-chip bonder, and the like.

[0104] The configuration of the parts-mounting apparatus according tothe present invention is not restricted to any of the configurationsshown in FIGS. 1 through 13. For example, an arbitrary configuration maybe employed for carrying out the process according to the presentinvention.

[0105] While description has been made regarding an arrangementaccording to the present invention wherein the first camera is disposedabove the suction head, and the second camera is disposed below thestage, the present invention is not restricted to this arrangement, butrather, some of the portions for receiving light (e.g., lens, mirror, orthe like) may be disposed above the suction head, and other portions forreceiving light may be disposed below the stage, i.e., there is no needto dispose a pair of main camera units respectively above the suctionhead and below the stage. Thus, an arrangement may be made wherein lightis cast onto a pair of main camera units disposed above, beside or belowthe suction head, or above, beside or below the stage, using multiplemirrors or prisms.

[0106] Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art.Therefore, the present invention is not limited by the specificdisclosure herein.

What is claimed is:
 1. A parts mounting method wherein a first part issuctioned by a suction head, and positioning is performed so as to mountsaid first part onto a second part held by a stage, said methodcomprising the steps of: preparing a first optical system with anoptical axis directed toward said suction head from above, and a secondoptical system with an optical axis directed generally facing theoptical axis of said first optical system, from below said stage;inserting said suction head between said first optical system and saidsecond optical system so that said first optical system takes an imageof a head reference mark provided to said suction head, which can beobserved from above, and so that said second optical system takes animage of said first part suctioned to said suction head; inserting saidstage between said first optical system and said second optical systemso that said first optical system takes an image of said second partheld on said stage, and so that the second optical system takes an imageof a stage reference mark provided to said stage, which can be observedfrom below; calculating the relative position between said first partand said suction head, and the relative position between said secondpart and said stage, based upon image information from said first andsecond optical systems; detecting said head reference mark and saidstage reference mark by said first and second optical systems with saidsuction head and said stage being positioned at the mounting position,and performing positional correction for at least one of said suctionhead and stage so that the positions of said first part and said secondpart satisfy a predetermined relation using the detected positionalinformation and said relative positional information; and following saidpositional correction, mounting said first part onto said second part.2. A parts mounting method according to claim 1, further comprising thestep of inserting a single calibration mark, which can be observed fromboth above and below, between said first optical system and said secondoptical system so that images of said calibration mark are taken by saidfirst optical system and said second optical system, whereby an offsetof the optical axes of said first optical system and said second opticalsystem is measured.
 3. A parts mounting method according to claim 2,wherein said calibration mark is provided to one of said suction headand said stage.
 4. A parts mounting method according to claim 1, whereinsaid first optical system and said second optical system are held with afixed positional relation during said step of taking images of said headreference mark and said first part, said step of taking images of saidsecond part and said stage reference mark, said step of performingpositional correction for at least one of said suction head and saidstage, and said step of mounting said first part onto said second part.5. A parts mounting method according to claim 1, wherein the positionalcorrection step for said suction head and said stage comprises the stepof said first and second optical system continuously taking images ofsaid head reference mark and said stage reference mark while heating oneor both of said suction head and said stage for bonding, whilecorrection is performed regarding the relative position between saidsuction head and said stage based upon said relative positionalinformation so that the positions of said first part and said secondpart have a predetermined relation.
 6. A parts mounting apparatus forpositioning and mounting a first part and a second part, said apparatuscomprising: a suction head, having a head reference mark which can beobserved from above, for suctioning said first part at a lower endportion of said suction head; a stage, having a stage reference markwhich can be observed from below, for holding a second part at an upperend portion of said stage; a driving mechanism for relatively movingsaid suction head and said stage in X, Y, Z, and θ directions; a firstoptical system for taking images of said second part held by the stage,and said head reference mark, from above said suction head; a secondoptical system, disposed so as to generally face said first opticalsystem with the optical axis thereof aligned with the optical axis ofsaid first optical system, for taking images of said first partsuctioned to said suction head, and said stage reference mark, frombelow said stage; a computation device for calculating the relativeposition between said first part and said suction head, and the relativeposition between said second part and said stage, based upon imageinformation from said first and second optical systems; and a controldevice for performing positional correction for said suction head andsaid stage so that the positions of said first part and said second partsatisfy a predetermined relation based upon said positional informationand said relative positional information from said first and secondoptical systems detecting said head reference mark, and stage referencemark with said suction head and stage being positioned at the mountingposition.
 7. A parts mounting apparatus according to claim 6, furthercomprising a positioning arrangement for continuously holding said firstoptical system and said second optical system in a fixed relation, atleast when said images are taken and at least until said suction headand stage are at said mounting position.
 8. A parts mounting apparatusaccording to claim 6, wherein at least one of said suction head and saidstage includes a part-suction opening; a hollow portion provided behinda back side of said part-suction opening and communicating with saidpart-suction opening; a transparent member, which closes the endopposite said part-suction opening of said hollow portion, whereby thepart-suction opening can be observed from the back side through saidtransparent member; and an air suction path connected to said hollowportion, and wherein at least one of said first optical system and saidsecond optical system detects said part-suction opening as said headreference mark or said stage reference mark through said transparentmember.
 9. A parts mounting apparatus according to claim 8, wherein aheater is fixed near said part-suction opening.
 10. A parts mountingapparatus according to claim 8, wherein the back side of said suctionhead or said stage is mounted to said driving mechanism by a bracketincluding a hollow portion, whereby said first or second optical systemcan be inserted for taking images of said part-suction opening throughsaid transparent member.